import java.util.Scanner;

public class Text1 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] arr = new int[n];

        for (int i = 0; i < n; i++) {
            arr[i] = sc.nextInt();
        }

        for (int i = 0; i < n; i++) {
            int ret = 1;
            for (int j = 0; j < n; j++) {
                if (arr[j] == arr[i] && i != j){
                    ret--;
                }
            }

            if (ret == 1){
                System.out.println(arr[i]);
            }
        }

    }
}
